1. Field of the Invention
The present invention relates to a method and an apparatus for transporting particles, such as polyolefin particles, through a pipe.
2. Related Background Art
It is a very important subject to prevent a pipe from being clogged with particles while particles are transported from one container to another container through the pipe.
For example, when polyolefin particles are produced by a gas phase polymerization method in a primary reactor and transported to a secondary reactor in a next process or a storage tank through a transportation pipe, it is conventional to use a purge tank as one of the transporting means After the particles are drawn from the reactor or the storage tank into the purge tank, a sufficiently pressure difference is provided between the purge tank and the following reactor or the storage tank thereby transport the particles at high speed.
In the conventional method, the clogging of the transportation pipe is prevented by transporting polyolefin particles at high speed. However, this means is still unsatisfactory, and there is a tendency to clog the transportation pipe.
There is a case that lump polymer is formed in the polymerization reactor in the reaction process. The lump polymer may stick and remain in the transportation pipe, which causes the clogging of the transportation pipe. Also, if the particles which still have reactive abilities remain in the pipe, the polymerization reaction proceeds and clogging of the pipe occurs. Once the transportation pipe is clogged, starting from the clogged part, the clogging gets worse and worse. In this condition, the transportation pipe may be removed to take out the clogging objects. This may unwillingly lead to the shut-down of the polymerization reactor or cut of the production.